Thanks for the guide. It was very helpful. There was just one extra thing I had to add in order for the passphrase prompt to always show up during start-up. In /etc/default/grub I edited GRUB_CMDLINE_LINUX_DEFAULT to look like:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash cryptopts=target=cryptswap1,source=/dev/sda6 resume=swap:/dev/mapper/cryptswap1"

Thanks for the guide. It was very helpful. There was just one extra thing I had to add in order for the passphrase prompt to always show up during start-up. In /etc/default/grub I edited GRUB_CMDLINE_LINUX_DEFAULT to look like:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash cryptopts=target=cryptswap1,source=/dev/sda6 resume=swap:/dev/mapper/cryptswap1"

I should mention two other things:
1. I only got hibernate to work with tuxonice.
2. By adding the line in the quote to /etc/default/grub (and then rebuilding with upgrade-grub2) I didn't need to edit /usr/share/initramfs-tools/scripts/local-top/cryptroot as mentioned in the guide at the beginning of this thread.